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Updated: Dec 29, 2025
Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43
Published on: September 11, 2020
Construction of a pneumolysin deficient mutant in streptococcus pneumoniae serotype 1 strain 519/43 and phenotypic
Vanessa S Terra1, Charles D Plumptre2, Emma C Wall3
1Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, United Kingdom.
Abstract:
Streptococcus pneumoniae capsular serotype 1 continues to pose a huge infectious disease burden in low- and middle-income countries, particularly in West Africa. However, studies on this important serotype have been hampered by the inability to genetically modify these strains. In this study we have genetically modified a serotype 1 strain (519/43), the first time that this has been achieved for this serotype, providing the methodology for a deeper understanding of its biology and pathogenicity. As proof of principle we constructed a defined pneumolysin mutant and showed that it lost its ability to lyse red blood cells. We also showed that when mice were infected intranasally with the mutant 519/43Δply there was no significant difference between the load of bacteria in lungs and blood when compared to the wild type 519/43. When mice were infected intraperitoneally there were significantly fewer bacteria recovered from blood for the mutant 519/43Δply strain, although all mice still displayed signs of disease. Our study demonstrates S. pneumoniae serotype 1 strains can be genetically manipulated using our methodology and demonstrate that the ability to cause pneumonia in mice is independent of active pneumolysin for the 519/43 serotype 1 strain.
Insights
Researchers genetically modified Streptococcus pneumoniae serotype 1, enabling new studies on this pathogen. A pneumolysin mutant showed reduced red blood cell lysis but similar pneumonia development in mice.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Streptococcus pneumoniae serotype 1 causes significant infectious disease burden, especially in West Africa.
- Genetic modification of S. pneumoniae serotype 1 strains has been a major limitation in studying its biology and pathogenicity.
Purpose of the Study:
- To develop and demonstrate a methodology for the genetic modification of Streptococcus pneumoniae serotype 1.
- To investigate the role of pneumolysin in the pathogenicity of S. pneumoniae serotype 1.
Main Methods:
- Genetic manipulation of a Streptococcus pneumoniae serotype 1 strain (519/43).
- Construction of a defined pneumolysin mutant (519/43Δply).
- Assessment of red blood cell lysis and bacterial load in mouse models (intranasal and intraperitoneal infection).
Main Results:
- Successfully achieved genetic modification of S. pneumoniae serotype 1 for the first time.
- The pneumolysin mutant lost its red blood cell lysis ability.
- Intranasal infection showed no significant difference in bacterial load between mutant and wild-type strains.
- Intraperitoneal infection with the mutant resulted in fewer bacteria in the blood, though disease signs persisted.
Conclusions:
- The developed methodology enables genetic manipulation of S. pneumoniae serotype 1 strains.
- Pneumolysin is not essential for causing pneumonia in mice with the 519/43 serotype 1 strain.
- This advancement facilitates deeper understanding of S. pneumoniae serotype 1 biology and pathogenicity.
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